Process for producing thermal and electrical insulating pads



Oct. 27, 1931. B. STCNEET AL 1,829,685

PROCESS FOR PRODUCING THERMAL AND ELECTRICAL INSULATING PADS Filed June l, 1928 "D Afl/7076 Patented Oct. 27, 1931 UNITED STATES rPATENT OFFICE BARNET STONE, HERBERT BEDSHAW AND JOHN WESLEY NUNNS, 0F GEORGETOWN, ONTARIO, CANADA, ASSIGNORS TO SMITH & STONE LIMITED, 0F GEORGETOWN,

ONTARIO, CANADA PROCESS FOR. PRODUCING THERMAL Application led .Tune 1,

This invention relates to an improved thermal and electrical insulating pad and process of producing same and more particularly to an insulating pad for use with hot plates for 5 electric stoves and the like. y

In the insulating pads at present in use porosity is obtained b mixing with the clay fugitive materials suc as cork. The process involved is known as the wet process in which the plastic clay is fashioned into sections which are then baked and machined to form insulating pads, the fugitive materials being consumed during the baking, leaving the completed pads porous.

We have discovered that by mixing and treating in. a dry state different clays in predetermined proportions and Without the addition of fugitive materials, in short, by a dust or dry process, thermal and electrical pads of sufficient porosity can be produced at a considerable reduction of cost, these results being attained by partially perforating the clay simultaneously with the operation of drying and pressing it, and whereby more rapid heating and cooling of the pad produced is provided.

In carrying out our improved dry process different kinds of clay, hereinafter more fully referred to, are mixed together and then pulverized. Sufficient Water to form the mixture into a slip is then added and the whole thoroughly agitated. The agitated slip is then filtered through a filter press to extract the water and the resultant product 5 dried by exposure to the air or in any other f Referring to these drawings in which like characters of reference indicate corresponding parts in each figure,

Figure 1 is a cross-section of an electric plate fitted with one of our improved pads.

Figure 2 is a plan view of the under side 192s. serial No. 282,211.

of the pad showing the partially extending perforations.

Figure 3 is an enlarged section on the line 8 3 of Figure 2.

Referring more particularly to the drawings, l0 designates a hot plate for electric stoves and the like of well known construction beneath which is fitted one of our improved insulating pads 11. This pad is formed on the under side with a plurality of staggered orifices 12 providing efficient and complete porosity as a result of which more rapid cooling and more rapid heating of the hot plate 10 is achieved. The upper face of the pad is smooth to fit more snugly against the plate 10, as shown in Figure l. A retaining plate 13 is shown on the under side of the pad and means are formed in the pad as at 14 for receiving therethrough bolts 15 for retaining the pad and hot plate rigidly together.

In carrying out the process we use the following ingredi'ents, ball clay, china clay, potters flint and sil-o-cel (diatomaceous earth) in approximately the following proportions by weight:

Ball clay 40 lbs. China clay 10 lbs. Spur body Potters flint 5 lbs.

The whole is then mixed in proportion as follows:

Spur body, 55 lbs. Raw sil-o-cel (diatomaceous earth) lbs.

made into a solution by the addition of water, thoroughly agitated and then passed through a filter press where the Water is extracted. The resultant product is dried, ground and finally pressed and perforated while being pressed. Before the final stage of pressing and perforating the completed mixture may be slightly moistened, if necessary, by the addition of approximately 2% of Water to bind the materials or a suitable binder may be employed. After the operation of pressing and partially boring or perforating the resultant forms are baked in well known manner to make the completed insulating pad.

As many changes could be made in the above construction and many apparently widely different embodiments of our invention, within the scope of the claim, construct-- ed with departing from the spirit or scope thereoi', it is intended that all mat-ter contained in the accompanying specification and drawings shall be interpreted as illustrative and not in a limiting sense.

TWhat We claim as our invention is:

A process `lor making pads of the type described ivithout the use of fugitive materials which consists of pulverizing and thoroughly mixing ball clay, china clay and potters iint to form a spur body, mixing said spur body with ravv sil-o-cel (diatoinaceous earth) adding Water to make a solution, thoroughly agitating said solution, filtering the solution, drying and then grinding the resultant mixture, adding a binder to the ground mixture, molding the mixture under pressure into partially perforated pads, and finally baking the pads.

In Witness whereof We have hereunto set our hands.

BARNET STONE. HERBERT REDSHAVV. JOHN WESLEY NUNNS. 

